The present disclosure relates to prosthetic heart valves. More particularly, it relates to stented prosthetic heart valves and related methods of use.
Diseased or otherwise deficient heart valves can be repaired or replaced with an implanted prosthetic heart valve. Conventionally, heart valve replacement surgery is an open-heart procedure conducted under general anesthesia, during which the heart is stopped and blood flow is controlled by a heart-lung bypass machine. Traditional open-heart surgery inflicts significant patient trauma and discomfort, and exposes the patient to a number of potential risks.
More recently, minimally invasive systems and techniques have been developed to facilitate catheter-based implantation of the valve prosthesis in the beating heart, intending to obviate the need for the use of classical sternotomy and cardiopulmonary bypass. With transcatheter (or transluminal) techniques, a valve prosthesis is compacted for delivery in a catheter and then advanced to the heart, for example through an opening in the femoral artery, subclavian artery, aorta, or ventricular apex to access the aortic valve. The delivered prosthesis is then deployed in the annulus of the valve to be replaced.
The heart valve prosthesis employed with transcatheter procedures generally includes an expandable, multiple-level frame or stent that supports a valve body having two or more leaflets. The actual shape and configuration of any particular prosthetic heart valve is dependent to some extent upon the native shape and size of the valve being repaired (i.e., aortic valve, mitral valve, tricuspid valve, or pulmonary valve). In general, prosthetic heart valve designs attempt to replicate the functions of the valve being replaced, and the stent utilized with the prosthesis dictates the final size and shape. In addition, the stent serves to anchor the transcatheter valve prosthesis at or about the native annulus.
One type of transcatheter valve stent frame can be initially provided in an expanded or uncrimped condition, then crimped or compressed about a balloon portion of a catheter. The balloon is subsequently inflated to expand and deploy the prosthetic heart valve. With other stented prosthetic heart valve designs, the stent frame is formed to be self-expanding. With these systems, the valve stent is crimped down to a desired size and held in that compressed state within a sheath for transluminal delivery. Retracting the sheath from this valve stent allows the stent to self-expand to a larger diameter, fixating at the native valve site. With either of these types of percutaneous stented prosthetic heart valve delivery devices, conventional sewing of the prosthetic heart valve to the patient's native tissue is typically not necessary.
In order to achieve necessary, long term anchoring at the native valve site, the stent frame must provide and maintain an elevated hoop strength and resistance to radially collapsing or compressive forces. A prosthetic valve that is not adequately anchored in place to resist the forces of the constantly changing vessel wall diameter, and turbulent blood flow there through, may dislodge itself, or otherwise become ineffective. In light of these requirements, transcatheter prosthetic heart valve stent frame designs are premised upon structural robustness, sufficient radial hoop strength or stiffness, and high fatigue strength. Further, the size or length of the stent is desirably selected to ensure elevated interface with the native anatomy. Lattice-type stent frame designs have been found to be well suited to meet these requirements, and are conventionally formatted to have a repeating pattern of closely sized, shaped and arranged cells. It has been found, however, that the stented transcatheter prosthetic heart valve may contribute to cardiac pacing issues post implantation. For example, it is estimated that approximately 10-30% of self-expanding transcatheter aortic valve procedures require pacemaker implantation.
In light of the above, a need exists for a stented transcatheter prosthetic heart valve with reduced impact on the conductive pathways of the heart.